| Year | Title | Role | Notes |
| 1960 | Mrs. Miniver | Carol Beldon | TV film |
| 1962 | ITV Television Playhouse | Carol | Episode: "The Morning After" |
| Man of the World | Carla | Episode: "The Mindreader" |
| 1963 | It Happened Like This | Joan | Episode: "Three of a Kind" |
| 1965 | The Man from U.N.C.L.E. | Eva | Episode: "The Adriatic Express Affair" |
| 1966 | Ben Casey | Joan Lloyd | Episode: "Pull the Wool Over Your Eyes, Here Comes the Cold Wind of Truth" |
| A Man Called Shenandoah | Paula | Episode: "The Imposter" |
| 12 O'Clock High | Sydney Vivyan | Episode: "The Slaughter Pen" |
| 12 O'Clock High | Helen Conboy | Episode: "Siren Voices" |
| Bob Hope Presents the Chrysler Theatre | Mary Lewis | Episode: "Time of Flight" |
| 1967 | Wings of Fire | Lisa | TV film |
| The Revenue Men | Jill Lacey | Episode: "Borderline" |
| Coronet Blue | Margaret Crowell | Episode: "Man Running" |
| 1968 | Sherlock Holmes | Grace Dunbar | Episode: "Thor Bridge" |
| 1969 | The Morecambe & Wise Show | Guest Star | Her father, Sir John Mills, guest starred in a later series. |
| 1970 | The Challengers | Mary McCabe | TV film |
| 1970–1971 | Nanny and the Professor | Phoebe Figalilly | Lead role (54 episodes) Nominated—Golden Globe Award for Best Actress in a Television Series – Musical or Comedy Nominated—Bravo Otto for Best Female TV Star |
| 1971 | Alias Smith and Jones | Julia Finney | Episode: "The Man Who Murdered Himself" |
| Stage 2 | Kate Hardcastle | Episode: "She Stoops to Conquer" |
| 1973 | Letters from Three Lovers | Maggie | TV film |
| The ABC Afternoon Playbreak | Susan Moroni | Episode: "Alone with Terror" |
| 1974 | QB VII | Samantha Cady | Miniseries Primetime Emmy Award for Outstanding Single Performance by a Supporting Actress in a Comedy or Drama Special |
| Born Free | Dr. Claire Hanley | Episodes: "Pilot", "The Flying Doctor of Kenya" |
| Harry O | Margaret Ballinger | Episode: "Ballinger's Choice" |
| Rex Harrison Presents Stories of Love | Usherette | Episode: "Kiss Me Again, Stranger" (Pilot-TV film) |
| 1975 | Marcus Welby, M.D. | Louise Carpenter | Episode: "Public Secrets" |
| Hawaii Five-O | Lady Sybil Danby | Episode: "Termination with Extreme Prejudice" |
| The Wide World of Mystery | Isobel | Episode: "Demon, Demon" |
| Matt Helm | Caroline Jeffries | Episode: "Death Rods" |
| 1976 | Ellery Queen | Florence Ames | Episode: "The Adventure of the Hardhearted Huckster" |
| Once an Eagle | Joyce | Miniseries |
| 1977 | Alexander: The Other Side of Dawn | Myra | TV film |
| Wonder Woman | Queen Kathryn | Episode: "The Queen and the Thief" |
| Barnaby and Me | Jennifer | TV film |
| 1978 | Switch | Alicia Alden | Episode: "Coronado Circle" |
| Police Woman | Amy Hollis | Episode: "Sixth Sense" |
| 1978–84 | Fantasy Island | Various | 4 episodes |
| The Love Boat | 8 episodes |
| 1979 | The Cracker Factory | Tinkerbell | TV film |
| 1980 | Hart to Hart | Kate Matthews | Episode: "Downhill to Death" |
| 1984 | Dynasty | Rosalind Bedford | Episodes: "The Secret", "That Holiday Spirit" |
| 1985 | All My Children | Judge Edith Hogan | TV series |
| 1985 | Hotel | Grace Cauldwell | Episode: "Fallen Idols" |
| 1987 | Murder, She Wrote | Annette Pirage | Episode: "Witness for the Defense" |
| 1987 | Hotel | Joanne Bentley | Episode: "Pitfalls" |
| 1988 | The Law & Harry McGraw | Isobel McKechnie | Episode: "Maginnis for the People" |
| 1989 | Judith Krantz's Till We Meet Again | Vivianne de Biron | Miniseries |
| 1990 | Monsters | Cara Raymond | Episode: "Outpost" |
| 1992 | Columbo | Eileen Hacker | Episode: "No Time to Die" |
